Method and apparatus for forming screw caps



. Feb. 19, 1946. G. zEs'BAUGH METHOD AND APPARATUS FORl FORMING SCREW CAPS Filed Sept. 12, 1942 Fis-'1.

(/fa Vfd #73 Fig-2.

N. N F

Figf

Patented Feb. 19, 1946 METHOD AND APPARATUS Fort FoRMrNG scaEw cAPs Lawrence G. Zcsbaugh, St.. Paul, Minn., assignor, by mesne assignments, to Perma-Seal Closure Co., St. Paul, Minn., a corporation Application SeptemberlZ, 1942, Serial No. 458,079

13 Claims.

This invention relates to a method and apparatus for forming a screw cap. With the present shortage of and restrictions on metal, eiiorts are being made to provide non-metallic containers.

One simple and inexpensive form of containerwould be one made of glass or other rigid nonmetallic material. Many containers now commercially used have an exteriorly threaded neck adapted to receive a screw cap or cover, which cap is of cup-shaped form and has an interiorly threaded flange.

It is an object of this invention to provide a very simple method and apparatus for making a screw cap out of fibrous material such as strong paper or cardboard.

It is a further object of the invention to provide dies of simple and efficient form in which a screw cap can be quickly and efliciently made of fabric material such as paper and/or cardboard.

It is another object of the invention to provide a novel, simple and eiiicient method for making a screw cap or cover from fabric material such as paper and/or cardboard.

It is a still another object of the invention to provide a set of dies of simple and eicient construction comprising a female die, a male die cooperating therewith and having a helical rib thereon constituting a thread-forming means and an annular die movable relatively to said male die and adapted to compress fabric material against said male die to form threads thereon.

These and other objects and advantages of the invention will 4be fully set forth in the following description made in connection with the accompanying drawing in which like reference characters refer to similar parts throughout the several views and in which:

Fig. 1 is an edge view of a sheet of material used as a cover sheet;

Fig. 2 is a central vertical section through a piece of sheet material used, the same being of cup-like form;

Fig. 3 is a central vertical section through a ring of fabric material;

Fig. 4 is a partial central vertical section through a set of dies used;

Fig. 5 is a central vertical section through a set of dies showing the same in cap-forming position, a portion of the male die being shown in side elevation;

Fig. 6 is a partial central vertical section through said dies showing the same in another position; 1

Fig. 7 is a partial central vertical section through the upper dies showing the partly completed cap thereon;

Fig. 8 is a partial central vertical section through a container showing the cap of the invention thereon; and

Fig. 9 is a partial view in elevation of a modified male die.

Referring to the drawing, a set of dies is shown comprising a female die Ill, the same having a ange Illa by means of which it will be secured to a suitable frame or bed I I by circumferentially spaced headed bolts I2. A. head I3 is shown which will be vertically movable in any suitable manner asby being connected to the reciprocating plunger of a standard machine. Member it has a ange I3a and an annular die It is secured to flange I3a by the circumferentially spaced headed -bolts I5 shown as having their heads countersunk in ange i3d. Die lli is provided with a cylindrical bore and is counterbored at its upper end to form an oiset or shoulder Ia. A male die I5 fits in and is slidable in the cylindrical bore of die I4, the same having acollar or ange Ia at its upper end, the lower side of which is adapted to engage the shoulder Illa. The male die I5 at its lower end is provided on its periphery with a helical rib I5b. Die I5 has a bottom flange l5c having a central opening ld therein. Die I5 is provided with a cylindrical bore and a plug orhead Il is disposed therein having a lower cylindrical iiange Ila, the lower side of which is of'frustoconical form and extends into opening I5d so that member I'l is centered in die I5. Member I'I has an upstanding cylindrical shank I lb which extends into the lower end of a coiled compression spring I3, the upper end of which engages the bottom of head I3. l

In carrying out the method of the invention in connection with the described apparatus a ring 20 is provided. This ring is of rigid form and is preferably made from brous material such as compressed paper or cardboard. A cup-like member 2l is formed from a sheet oi strong paper or similar material and a cover sheet 22 is also preferably provided. The female die I0 has a cylindrical recess Illb therein and ring 20 snugly ts in this recess. Ring 2t is placed in recess |0b and the member 2l is placed on the ring as shown in Fig. 4. The dies I4 and I5 are at this time in raised position as shown in Fig. 4. With the parts disposed as shown in Fig. 4, the head I3 is now moved downwardly and the lower end of male die I5 moves into cup 2| and forces the same downwardly moving the same into the ring 20 so that it is very firmly engaged with ring 20 and permanently secured thereto. The bottom of the cup 2| now extends across the bottom of ring 20. The rim or flange forming the side f the cup as disposed along the inner side of ring 20. This may move somewhat in between the convolutions of rib Ib owing to its firm engagement `with ring and the resulting lateral pressure toward the periphery of die I5. When the male die I5 reaches the position shown in Fig. 5, its further downward' movement is stopped by the female die I0. The head I3 however, continues to move downwardly and the annular die I4 thus moves downwardly, the spring I8 being compressed. The lower end of the annular die I4 now moves within the cylindrical recess in the female die I0 and engages the top of the ring 20. The ring is now compressed and the material thereof-and the material forming the' side of the cup portion 2| is forced inwardly to very firmly engage the exterior of the male die I5 and completely fill the groove between the ribs I5b. This final position of the dies is shown in Fig. 6. The head I3 is now raised and dies I4 and I5 are raised. 'I'he annular die I4 moves to its upper position as shown in Figs. 4 and 7, due to the expansion of spring I8 and the cap or coverformed is lifted upwardly with and on male die I5 as shown in Fig. 7. The cap is removed by rotating the same off of the male die, the same readily moving off of the die due to the threads on the die and the'threads which have been formed on the cap. Preferably a cover is placed over the cap as shown in Fig. 8 and this can be done in any suitable manner as by forcing the cover and sheet 22 into a die having a cylindrical recess therein. Alternately the sheet 22 could be formed into a cup and the cap placed therein and secured in any suitable manner either by friction or by an adhesive. The finished cap would then appear as shown in Fig. 8, and the same can be screwed onto a container 25 having a threaded neck 25a thereon. In Fig. 9 the male die I5 is shown with circumferentially spaced rib portions I5bb forming depressions or grooves I5cc. Grooves or depressions I5cc are formed between rib portions I5bb. Rib portions I5bb are staggered in successive rows and are somewhat greater in extent than grooves I'Scc so that they overlap slightly in successive rows. The spaced rib portions I5bb and intervening grooves I 5cc constitute interrupted annular ribs. When the flange of the cap is forced against said ribs I5bb projections will be formed thereon by the material entering the grooves I5cc. These projections will give a yielding or resilient effect to the cap flange when it is placed in a non-threaded neck or top of a container or one which is cylindrical. This will provide friction and assist in holding the cap firmly in position.

- From the above description it will be seen that I-have provided a simple method and apparatus for forming a simple, rigid and durable cap of material such as paper or cardboard. The cap can thus be very quickly and inexpensively produced. The material used can be waterproofed and a very efficient and durable cap is produced and one which will serve in practically all cases just as well as a metal cap or a cap formed of any other material. The method and apparatus have been amply demonstrated in actual practice and found to be very successful and efficient.

It will, of course, be understood that various changes may be made in the form. details, arrangement and proportions of the apparatus and in the steps and sequence of steps of the method without departing from the scope of applicants invention, which generally stated, consists in a method and apparatus capable of carrying out the objects above set forth, such as disclosed and dened in the appended claims.

What is claimed is:

1. 'Ihe method of making a screw cap which consists in providing a rigid ring of fabric material, placing the same in a cylindrical die in which it substantially fits, forming a sheet of material into substantially cup-shaped form, placing said cup on said ring with its bottom extending thereacross, forcing said cup into said ring to closely t therein and form a cap having a cylindrical flange and forming threads on the inner side of said cap by compressing the same longitudinally and forcing it against the side of a thread-forming die.

2. The method of forming a screw cap which consists in forming a rigid ring of cardboard material, forcing a, sheet of paper-like material into said ring to extend across and along the sides thereof thus forming a cap having a peripheral flange, pressing threads on the flange of said cap and placing a cover of sheet material over the top and periphery of the ange of said cap.

3. An apparatus for forming a cap comprising a cylindrical female die adapted to receive an annular ring, a male die having an external diameter approximating theinternal diameter of said ring and having a helical rib thereon, said male die being adapted to force a cup-like piece of sheet material into said ring in said female die and an annular die movable on said male die for compressing said ring and forcing the same and said .sheetl into the groove formed by said helical rib to form a thread on said cap.

4. An apparatus for forming a cap comprising a cylindrical female die adapted to receive an annular ring, a male die having an external diameter approximating the internal diameter of said ring and having spaced projections and depressions thereon, said male die being adapted to force a cup-like piece of sheet material into said ring in said female die and an annular die movable on said male die for compressing said ring and forcing the same and said sheet into said depressions to form projections on said cap.

5. A method of making a screw cap which consists in providing a rigid ring, placing the same in a cylindrical die having a diameter approximating the outer diameter of said ring, placing a sheet of flexible material over said ring, forcing said sheet into said ring with a die having a helical rib on its periphery disposed closely adjacent the inner side of said ring, exerting pressure on the top edge of said ring to compress it in the direction of its axis and reduce its longitudinal dimension s0 that it is expanded laterally and its inner side and the portion of said sheet about said side are forced against said helical rib and a thread formed on the same.

6. The method of forming a screw cap which consists in providing a rigid ring, placing the same in a cylindrical die, having a diameter approximating the outer diameter of said ring, inserting a die inside of said ring having a diameter approximating that of the inner side of said ring and having a thread on its periphery, comprising said ring longitudinally to reducev its longitudinal dimension and expand it laterally to force it against said periphery to form a thread thereon.

7. 'I'he method of forming a screw cap which consists in forming a rigid ring of cardboard material, forcing a sheet of paper-like material into said ring to extend across and along the inner side thereof and be frictionally connected thereto, said sheet and ring thus forming a cap and said ring and the portion of said sheet along its inner side forming a flange, compressing said flange longitudinally to reduce its longitudinal dimension and expand it laterally against a die having a helical rib thereon to form a thread on said flange. i

8. The method of forming a screw cap which consists in providing a rigid ring, placing a sheet of flexible material across said ring, forcing said sheet into said ring whereby a cap is formed with said ring and the portion of said sheet at the inner side thereof forming a flange, exerting end-wise pressure on said flange to compress it longitudinally to reduce its longitudinal dimension and force it laterally against a die to form threads thereon.

gagement with said top, a third annular die fitting about said male die and movable longitudinally thereof into said space and into engagement with the upper edge of said flange, means rigidly secured to said third die for moving it and a yielding means between said last mentioned means and said male die so that said male die will seat against said flat bottom and relative movement will then occur between said third die and male die as the latter moves into said recess said annular die acting to compress said flange and force it against said ribs.

10. The structure 4set forth in claim 9, said male die having an interrupted annular rib thereon adapted to form spaced depressions in a cylindrical article forced thereagainst.

11. 'I'he method of forming a screw cap which consists of forming a cap of compressible material such as paper or cardboard, the same having a cylindrical flange thereon, pressing the top of said cap in inverted position against the flat bottom of a cylindrical die by means of a male die having a flat lower end and a helical rib on its exterior and then engaging the edge of said flange with an annular die fitting about said male die and movable into said cylindrical die to engage the edge of said flange and force said flange against said helical rib to form a thread on said flange.

l2. An apparatus for forming a screw cap having in combination, a cylindrical die having a flat bottom and a cylindrical wall adapted to receive a cap in inverted position with its top engaging said flat bottom and having a flange substantially engaging said cylindrical wall, a male die having a flat lower end movable into said cylindrical die to engage said top of the cap and hold it against the bottom of said cylindrical die, said male die having a helical rib on its periphery at its lower end portion adapted to be disposed within said flange and an annular die tting about said male die and movable into and fitting in said cylindrical die to engage the edge of said flange and compress the same and force it'against said helical rib to forma thread on said flange,

13. An apparatus for forming a screw cap, said cap having a top and a peripheral relatively thick flange having in combination, a female die having a recess therein with a cylindrical wall and a flat rigid bottom extending at right angles to said wall, a male die adapted to move into said recess to within a slight distance from the bottom thereof and having peripheral ribs adjacent its end, said cap being disposed in said recess with its top engaging said bottom and said flange projecting upwardly, said top being pressed be` tween said male die and said bottom, and a third annular die movable into said recess between said male die and said wall to engage the edge of said flange and force it against said ribs.

LAWRENCE G. ZESBAUGH. 

